Magnetic recording medium

Abstract

A magnetic recording medium comprising a substrate, a magnetic layer formed on the substrate and comprising a metallic magnetic material as a recording element and a protective layer formed on the magnetic layer and comprising a perfluroalkyl polyether derivative having a phosphate terminal group, which has improved durability and corrosion resistivity.

What is claimed is: 
     
       1. A magnetic recording medium comprising a substrate, a magnetic layer formed on the substrate and comprising a metallic magnetic material as a recording element and a protective layer formed on the magnetic layer and comprising a perfluroalkyl polyether derivative having a phosphate terminal group. 
     
     
       2. A magnetic recording medium according to claim 1, wherein the perfluroalkyl polyether derivative having a phosphate terminal group is a compound of the formula: ##STR5## wherein A is a group of the formula:   --[CF(CF.sub.3)--CF.sub.2 O]--,       --(CF.sub.2 CF.sub.2 O)-- or       --(CF.sub.2 O)--     B is a group of the formula:     --(CF.sub.2 COO)-- or       --[CF(CF.sub.3)--COO]--     X is hydrogen or fluorine, R is hydrogen, fluorine, methyl, trifluoromethyl or chloromethyl, n is an integer of 10 to 50 and m is an integer of 1 to 50.   
     
     
       3. A magnetic recording medium according to claim 1, wherein an amount of the perfluroalkyl polyether derivative having a phosphate terminal group to be coated is from 0.01 to 30 mg/m 2 . 
     
     
       4. A magnetic recording medium according to claim 1, wherein the substrate is a tape. 
     
     
       5. A magnetic recording medium according to claim 1, wherein the substrate is a disc. 
     
     
       6. A magnetic recording medium according to claim 1, wherein the substrate is a drum. 
     
     
       7. A magnetic recording medium according to claim 1, wherein the substrate is made of polyethylene terephthalate. 
     
     
       8. A magnetic recording medium according to claim 1, wherein the magnetic layer comprises metallic magnetic powder. 
     
     
       9. A magnetic recording medium according to claim 8, wherein the metallic magnetic powder is selected from the group consisting of Fe powder, Co powder and Fe-Ni powder. 
     
     
       10. A magnetic recording medium according to claim 1, wherein the magnetic layer comprises a ferromagnetic thin film. 
     
     
       11. A magnetic recording material according to claim 10, wherein the ferromagnetic material is selected from the group consisting of Co, Ni, Fe, Co-Ni, Co-Cr, Co-P and Co-Ni-P.